/Engine/Plugins/Runtime/XRBase/Source/XRBase/Public/XRTrackingSystemBase.h
If the device id represents a head mounted display, fetches the relative position of the given eye relative to the eye. If the device is does not represent a stereoscopic tracked camera, orientation and position should be identity and zero and the return value should be false.
true if the pose is valid or not. If the device is not a stereoscopic device, return false.
virtual bool GetRelativeEyePose ( int32 DeviceId, int32 ViewIndex, FQuat & OutOrientation, FVector & OutPosition )